Constant-speed reciprocable hydropneumatic motor



March 5, 1963 .1.K1RscH 3,079,897

CONSTANT-SPEED RECIPROCABLE HYDRO-PNEUMATIC MOTOR Filed Nov. 29. 1960 -j-'l v ArroAM/fs 3,679,897 CONSTANT-FEED RECHRGCABLE HYDE@- PNEUMATEC MGTR Serry Kirsch, 3946 Bishop Road, Detroit 24, Mich. Filed Nov. 29, 1360, Ser. No. 72,476 Claims. (Cl. 121-38) This invention relates to reciprocable fluid pressure motors and, in particular, to reciprocable hydro-pneumatic motors containing a relatively incompressible working fluid, such as a liquid, and also a compressible working uid, such as a gas.

One object of this invention is to provide -a reciprocable hydro-pneumatic motor having a reciprocable hollow piston, the head of which contains a flow control valve which automatically produces a constant rate of flow of hydraulic pressure fluid from one side of the piston head to the other side thereof, the hollow piston containing a free or floating internal piston with a compressed gas, such as nitrogen, on the opposite side of the floating piston from the hydraulic duid, thereby causing the hollow piston rod to move at a constant speed out of its cylinder.

Another object is to provide a reciprocable hydropneumatic motor of the foregoing character wherein the flow control valve includes a sleeve Valve member which is movable against opposing spring pressure to open or close or reduce the size of cooperating ports as the hydraulic pressure varies within the hollow piston rod, thereby causing the hydraulic fluid to emerge from the piston head into the main cylinder chamber at a constant rate of flow which produces a constant speed of travel of the piston and cylinder relatively to each other.

Another object is to provide a reciprocable hydropneumatic motor of the foregoing character wherein the reciprocable sleeve valve member is mounted in a ported sleeve which in turn is stationarily mounted in the head of the hollow piston.

ther objects and advantages of the invention will become apparent during the course of the following description of the accompanying drawings, wherein:

FGURE l is a central vertical section through a reciprocable hydro-pneumatic motor adapted to produce a constant piston speed, according to one form of the invention, with the piston shown in its fully closed position ready to commence its opening stroke;

FGURE 2 is a view similar to the upper end of FlG- URE l, but with the sleeve valve member of the llow control valve in the hollow piston head in its actuating position closing oli a portion of the ow of hydraulic fluid from the intermediate chamber within the hollow piston rod to the main chamber within the cylinder of the motor, with the parts shown in the positions occupied shortly after the commencement of the opening stroke of the motor; and

FIGURE 3 is a View similar to FIGURE 2 but showing a modified motor with the flow control valve in the hollow piston head in a reverse direction providing regulated flow of the iiuid during the closing stroke therein shown and free iiow during the opening stroke, which is the opposite of the arrangement shown in FIGURES l and 2.

Referring to the drawing in detail, FIGURES l and 2 show a constant speed reciprocable hydro-pneumatic motor, generally designated 10, according to one form of the invention as consisting generally of a main cylinder 12, a hollow piston 14 reciprocable within the main cylinder 12, a free or floating piston 16 reciprocable within the hollow piston le, and a constant speed flow control valve 18 mounted in `the head of the hollow piston 14. The hollow piston 14 externally of the main cylinder l2 is closed by a hollow cap 2d. rIhe motor 16, by reason of the above construction, possesses a main or inner hy- 3,679,897 Patented Mar. 5, 1963 draulic chamber Z2 above the hollow piston 14, lan intermediate or middle hydraulic chamber 24 above the free piston 16, and a pneumatic -or outer chamber 26 below the free or floating piston 16.

The main cylinder 12 is provided with `an end wall 23 containing a threaded hydraulic fluid filling port 25 closed by a lthreaded plug 27 and with a cylinder bore 28, the upper portion of which forms the main hydraulic chamber 22.. The lower end portion of the main cylinder 12 is eX- ternally threaded and has threaded thereon a' stop collar or closure collar 30 having a bore 32 therethrough of slightly smaller diameter than the main cylinder bore 2S with `an annular shoulder 34 therebetween. The closure collar 3o has an internally-grooved open end 36 to receive a scraper ring 38.

The hollow piston 14 includes a piston head ril reciprocable in the rnain cylinder bore 2S Land a hollow piston rod of smaller diameter which extends downwardly therefrom through the bore 32 in the stop collar 36, thereby providing an annular shoulder e3 between the hollow piston head 4% and hollow piston rod 4Z and also an annular space i4 between the piston rod 42 and the cylinder bore 2S which is vented tothe atmosphere by a radial vent port 46. The lower end of the hollow piston rod 42 (FGURE l) is externally threaded to receive the internally-threaded upper end of the closure cap 2i). The latter is provided with a central internally-threaded hole t8 into which is lthreaded a charging fitting Sti which in turn is internally bored and threaded to receive a springpressed filling valve 5l resembling a pneumatic tire filling valve and threaded externally to receive a closure cap 52. The closure cap Ztl is provided with -a cup-shaped recess 54, the mouth of which is internally-threaded to receive a correspondingly-threaded closure disc 56 sealing ot the recess 54. The charging fitting 59 is provided for the purpose of charging the pneumatic or lower chamber 26 with a compressed gas, such -as air or nitrogen, after which the plug 52 is tightened and the closure disc 56 inserted to close the mouth of the recess 54.

The hollow piston rod 42 is provided, as its name suggests, with a longitudinal piston rod bore 58 which in itself serves as a cylinder bore in which the free or floating piston 16 freely reciprocates. The latter is externally grooved to receive an O-ring or other sealing ring 60. The upper end of the piston rod bore 58 is counterbored as at 62 to receive the constant speed flow contro-l valve i8, which is mounted in the hollow piston head 49 in the correspondingly-threaded upper tlange 6d on the upper end of a valve casing 66 which also completes the piston head 4%. T he valve casing 66 is spool-shaped with its threaded upper flange 64, a reduced-diameter neck portion 63 and a lower flange 76 which is externally-grooved to receive a sealing ring 72, such as an O-ring. The hollow piston rod 4t? is also externally grooved at axially-spaced loc-ations to receive sealing rings 74, such `as O-rings. The gasket 3S and the sealing rings 6i), 72 4and 74 are preferably of elastic deformable material, such as natu-ral .or synthetic rubber or compositions thereof.

The upper flange 64 of the valve casing 66 is provided with axial ports 7 6 extending therethrough from the main or upper hydraulic chamber 22 to the annular space or chamber 78 between the upper and lower valve casing flanges 64 and 7d. The neck portion 63 of the valve casing 66 is provided with radial ports Si? extending therethrough from the annular valve casing chamber 7g to a valve bore S2 extending axially into the valve casing 66 from the lower end thereof, which is internally-grooved to receive a snap ring or retaining ring 34. The upper end of the valve bore 82 terminates within the upper flange 64 and is there provided with a vent port 86 opening into the main cylinder chamber 22 from a spring chamber 88 formed by the upper end yof the valve bore 82 and containing a helical compression spring 90.

The compression spring 90 at its upper end is seated against the upper liange'64 surrounding the vent 86v and at -its lower end engages the annular upper-end. 92 of a cup-shaped sliding sleeve-valve' member 94 forming the.

moving part of the flow control valve 13. The cup-shaped sleeve valve memberv 94'V is providedV with a skirt 96 containing a pluralitysofradialY circumferenti-ally-sp'aced.. ports 98 disposedon the samerlevel las the 'valve casingv ports 80 ini-'the lowerm-ostf position vof ythe sleeve valve member 94fwhen lurged bythe `compression spring 90 against the snap-ring 34 (FIGURE 1). The radial ports 9S-in-the ski-rt 96 of the sleevevvalve-'member 94 `are in terconnected by an annularexternal groove' 106. inthe skirt 96, so that the ports 98 are not required to remain f inradial alignment with theports S in order to effect4 communication therewith. The sleeveV valve-member 94 adjacent the snap ring 34 has -an end wall 1ti2`providedseated in :a part engageable with a movable member such'v as la press platen, whilethe cap on the end of the hollow piston rod 14 is seated in a relatively stationarypart; such -as ina die to return a cam slide after closing thereof. Let vit also be assumed that the upper or1mainy hydraulic chamber 22 has been filled with hydraulic fluid, such as oil, ythrough the port while the main cylinder endv wall `23 is located at its maximum distance away from the hollow piston head 40, so that the annular Shoul-y ders 43 -and 34 are in close proximity to one another or in direct engagement with one another. This constitutes the open or extended position of the motor 10 in contrast with the compressed or closed posi-tion shown in FIG-y URES l `and 2. Let it inally beassumed that the lowerl chamberY 26 has been chargedwith an expansible fluid such as a compressed gas, compressed nitrogen being preferred because of its inert characteristics, this being accomplished by meansof Ia hose (not shown) having a coupling engaging the Vexternally-threaded filling valve 51 in the absence of thel closure cap 52 and closure disc 56"(FIGURE l). When the parts are in the open posi'- tion of the motor 10, the iioating piston 1.6 is forced by the compressed gas within' the lower or pneumatic chamber 26 =int0 close proximity with the lower -ange `7|) of the valve casing 66. Y l

As the press platen or other moving member-*connected to oren'gaging the main cylinder'12 carries out its dow-nward or working stroke, suchl as by the descent of a` press platen, -ther platenor other moving part carries downward with it the main cylinder 12. This vaction forces hydraulic fluid from the substantially Yfullvrupper or main hydraulicchamber 22 and causes the tiuidto flow freely throughthe ports -76, lthe annular external valve casing cham-ber 78, the now-aligned or fully open ports 80 and 98 so maintained by the urge of the compression spring 90, and the end port 164 of the sleeve valve member 94 into the intermediate or middle hydraulic',V chamber 24. The accumulation of hydraulic pressureY uid in the intermediate or middle chamber 24 acts against' the' free or floating piston 16 and forcesit downward toward the position shown in FIGURE l, further compressing the vgas'or other expansible uid within the lower or pneumatic chamber 26. In this manner, the lower chamber 26 andthe floating vpiston 16 act in a manner similar 'to Ta pneumatic accumulator ofv hydraulic' pressure 11u-id,'storingV lup potential energy inthe lower chamber 26. f When the downward motion of the main cylinder 12 relatively to the hollow piston 14'isterminated (FIGURE 2'), and the maincylinder 12 isreleased to'move 'up- Ward2the compressed gas' -in VAth'e lower chamber 26 vacting ll against the oating piston -16 moves .the lat-ter upward. This yaction expels hydraulic iluid from the intermedi-ate hydraulic chamber 24 through the lower end portk 104 and radial skirt ports 98 through the casing ports 80 and 76 into the upper or main hydraulic chamber 22, causing a pressure drop or differential pressure to be created on opposite sides vof the end port 104'as a resultV of the Venturi effect of fluid flow therethrough;

The instant thecylinder 12."ofthe motor y10 of FIG- URES 1 and 2 starts moving upward (FIGURE 2) after reaching .the bottomotits stroke (FIGURE l), the sleeve downward, causing its port 98 to move into wider opening relationship with the .ponts Si) and thereby increasing theA flow Iof iiuid lthrough the increased resultan-t area.

In one form of the. valve 10 as actually constructed and successfully tested, it Ahas beenv found that at highv pres-Y sures the tiuid How does not exceed the rate of ten galf lonsvper minute and maintainsv a constant volumetric now of hydraulic uid over a wide range of variation of pneu-V matic pressures in the end chamber 26V and a consequent Wide range of variation of hydraulic pressures in Vthe mid-,

dle chamberV `24. In theabove-mentioned motor 10 kas constructed, the lower or pneu-matic cham-ber or. endY chamber 26' is prech-arged, in the open position of the motor 10, with compressedY air at av pressure of 300 pounds per square inch which builds upto a pressure of v1800 to; 2000 pounds per squareV inchin the closed position of -the` motorltl shown in FIGURE 1. The freeoroatng piston 16 during operationfnever moves :into actualcontact with the valve casing flange 70 because an excessive amount ofoil is vprovided in the middlech-amber 24and$ other communicating spaces in the motor 10 tocompensate for anylossof oil by leakage;

The modified hydro-pneumatic motor, .generally desig-.l

nated'110 shown in FIGURE 3 is generally similar in con-V struction to the hydro-pneumatic motor 10 shown in FIG- URES 1 and 2, but differs in details of construction and arrangement, hencecorresponding parts are designated. numerals increased by` one the flow regulating valve with corresponding Areference hundred. Most importantly, member 194 of the valve 118 of the motor 110 is mounted in -a reversed position fromthat of the valve member 94jv shown in the motor 10 ofFIGURES l and..2. In thisY reversed position, the hydro-pneumatic motor provides regulated flow of uid at a constant rate during its closingl stroke, as-shown in FIGURE 3, and free now during its" opening stroke, n contrast to -the motor 10 of FIGURESy 1 andv 2, .which provides regulated iow of fluid at a con-V stant rate during its itsclosing stroke. In either form of :the invention, it is not primarily the. pressure of the working Huid, name-lyV the hydraulic iiuid,` which shifts the valve spool or movable valve member, but rather the owof uid through the end orifice thereof creating a venturi etect of reduction in pres-Yr sure as a resultof ow through the end orifice of the valve member, which in turn results inan increase in the pressure differential on opposite sides of that oriiice.

The'modied hydro-pneumatic motorllt) Ais provided` with a main cylinder 112, a hollow piston 114 reciprocable a free or iloating 'piston'116 of FIGURES 'f 1'and'2 and similarly mounted for reciprooation withinthe hollow piston-144, andra constant speed flow control'v'alv'e 118fmounted in the headV of the'hollow piston 114 but: withits sleeve valve` member 194 mounted -ina reversed? position as compared with the sleeve valve member 942 within the main cylinder 112, (not shown) similar to the floating piston 16 ofrFIGURESLl and Other-distinctions of construction.

opening stroke and free ow during,

of the modilied hydro-pneumatic motor llt? are that the threaded upper llange ldd on the valve casing 166 is solid and not provided with ports, whereas the lower flange 179 is provided with axial ports 76 correspondinU to the ports 76 in the upper flange 64 of the valve casing 66 o the motor 19 of FGURES 1 and 2.

'The operation of the modified hydro-pneumatic motor, generally designated 11i) of FlGURE 3 is consequently the reverse of that of the hydro-pneumatic motor 1li described above and shown in FIGURES 1 and 2.

What l claim is:

l. A unidirectionally constant-speed reciprocable hydropneumatic motor comprising a cylinder having a cylinder bore therein and having a closed end and an open end, a restrained piston reciprocably mounted in said cylinder bore, said restrained piston having a piston head delining with said cylinder bore and closed end an inner chamber adapted to contain hydraulic fluid, said restrained piston having a hollow restraining piston rod extending from said piston head outwardly through the open end of said cylinder and having la closed outer end, said piston rod having a longitudinal bore therein, a tree piston floatingly mounted in said restrained piston rod bore and delining with said piston head a middle chamber adapted to contain hydraulic uid and dening with said closed piston rod end an outer chamber adapted to contain a compressed pneumatic lluid, and yieldingly-urged valve means in said piston head hav-ing a valve passageway of variable cross-sectional area interconnecting said inner and middle chambers, said valve means being responsive to the tlow o hydraulic iluid in one direction between said middle chamber and said inner chamber resulting from relative motion between said cylinder and `said restrained piston in one direction for varying the effective cross-sectional area of said valve passageway to maintain a substantially constant rate of liow of hydraulic fluid through said passageway in said one direction of hydraulic ui llow, said valve means including a movable valve member and resilient means urging said valve member in a passageway-opening direction, said valve member having an orice therein responsive to flow of hydraulic fluid therethrough to create a differential pressure on oppositeI sides thereof to move said valve member in the direction of said ilow in a passageway-closing direction which in cooperation with the opposing urge of said resilient means upon said valve member varies the cross-sectional area of said valve passageway to maintain a constant rate o hydraulic fluid llow in one direction therethrough and consequently to impart a constant speed of reciprocation of said motor in one direction irrespective of the variation of hydraulic pressure within said motor.

2. A unidirectionally constant-speed rcciprocab-le hydropneurnatic motor, according to claim 1, wherein said valve means provides substantially free llow of hydraulic iluid in the opposite direction from said one direction of hydraulic fluid flow.

3. A unidirectionally constant-speed reciprocable hydropneumatic motor, according to claim 2, wherein said valve member is a sleeve with said port on the side wall thereof.

4. A unidirectionally yconstant-speed reciprocable hydropneurnatic motor, according to claim 3, wherein said restrained piston head has a bore in which said sleeve valve member is reciprocable, said bore having a side wall with a port therein registrable with the side wall port of said sleeve valve member.

5. A unidirectionally constant-speed reciprocable hydropneumatic motor, according to claim 1, wherein said restrained piston head has a passageway therethrough and a port in said passageway and wherein said valve means includes a movable valve member having a passageway therethrough and a port in said passageway registering with said restrained piston head passageway port.

References Cited in the tile of this patent UNITED STATES PATENTS 2,676,573 Abbo Apr. 27, 1954 2,679,827 Perdue June 1, 1954 2,845,086 Waternian et al July 29, 1958 2,845,987 Thomas July 29, 1958 2,994,301 Kirsch Aug. 1, 1961 

1. A UNDIRECTIONALLY CONSTANT-SPEED RECIPROCABLE HYDROPNEUMATIC MOTOR COMPRISING A CYLINDER HAVING A CYLINDER BORE THEREIN AND HAVING A CLOSED END AND AN OPEN END, A RESTRAINED PISTON RECIPROCABLY MOUNTED IN SAID CYLINDER BORE, SAID RESTRAINED PISTON HAVING A PISTON HEAD DEFINING WITH SAID CYLINDER BORE AND CLOSED END AN INNER CHAMBER ADAPTED TO CONTAIN HYDRAULIC FLUID, SAID RESTRAINED PISTON HAVING A HOLLOW RESTRAINING PISTON ROD EXTENDING FROM SAID PISTON HEAD OUTWARDLY THROUGH THE OPEN END OF SAID CYLINDER AND HAVING A CLOSED OUTER END, SAID PISTON ROD HAVING A LONGITUDINAL BORE THEREIN, A FREE PISTON FLOATINGLY MOUNTED IN SAID RESTRAINED PISTON ROD BORE AND DEFINING WITH SAID PISTON HEAD A MIDDLE CHAMBER ADAPTED TO CONTAIN HYDRAULIC FLUID AND DEFINING WITH SAID CLOSED PISTON ROD END AN OUTER CHAMBER ADAPTED TO CONTAIN A COMPRESSED PNEUMATIC FLUID, AND YIELDING-URGED VALVE MEANS IN SAID PISTON HEAD HAVING A VALVE PASSAGEWAY OF VARIABLE CROSS-SECTIONAL AREA INTERCONNECTING SAID INNER AND MIDDLE CHAMBERS, SAID VALVE MEANS BEING RESPONSIVE TO THE FLOW OF HYDRAULIC FLUID IN ONE DIRECTION BETWEEN SAID MIDDLE CHAMBER AND SAID INNER CHAMBER RESULTING FROM RELATIVE MOTION BETWEEN SAID CYLINDER AND SAID RESTRAINED PISTON IN ONE DIRECTION FOR VARYING THE EFFECTIVE CROSS-SECTIONAL AREA OF SAID VALVE PASSAGEWAY TO MAINTAIN A SUBSTANTIALLY CONSTANT RATE OF FLOW OF HYDRAULIC FLUID THROUGH SAID PASSAGEWAY IN SAID ONE DIRECTION OF HYDRAULIC FLUID FLOW, SAID VALVE MEANS INCLUDING A MOVABLE VALVE MEMBER AND RESILIENT MEANS URGING SAID VALVE MEMBER IN A PASSAGEWAY-OPENING DIRECTION, SAID VALVE MEMBER HAVING AN ORIFICE THEREIN RESPONSIVE TO FLOW OF HYDRAULIC FLUID THERETHROUGH TO CREATE A DIFFERENTIAL PRESSURE ON OPPOSITE SIDES THEREOF TO MOVE SAID VALVE MEMBER IN THE DIRECTION OF SAID FLOW IN A PASSAGEWAY-CLOSING DIRECTION WHICH IN COOPERATION WITH THE OPPOSING URGE OF SAID RESILIENT MEANS UPON SAID VALVE MEMBER VARIES THE CROSS-SECTIONAL AREA OF SAID VALVE PASSAGEWAY TO MAINTAIN A CONSTANT RATE OF HYDRAULIC FLUID FLOW IN ONE DIRECTION THERETHROUGH AND CONSEQUENTLY TO IMPART A CONSTANT SPEED OF RECIPROCATION OF SAID MOTOR IN ONE DIRECTION IRRESPECTIVE OF THE VARIATION OF HYDRAULIC PRESSURE WITHIN SAID MOTOR. 